Use of the polymerase chain reaction in the quantitation of mdr-1 gene expression

bfc, a novel serpent co-factor for the expression of croquemort, regulates efferocytosis in Drosophila melanogaster

Efferocytosis is the process by which phagocytes recognize, engulf, and digest (or clear) apoptotic cells during development. Impaired efferocytosis is associated with developmental defects and autoimmune diseases. In Drosophila melanogaster, recognition of apoptotic cells requires phagocyte surface receptors, including the scavenger receptor CD36-related protein, Croquemort (Crq, encoded by crq). In fact, Crq expression is upregulated in the presence of apoptotic cells, as well as in response to excessive apoptosis. Here, we identified a novel gene bfc (booster for croquemort), which plays a role in efferocytosis, specifically the regulation of the crq expression. We found that Bfc protein interacts with the zinc finger domain of the GATA transcription factor Serpent (Srp), to enhance its direct binding to the crq promoter; thus, they function together in regulating crq expression and efferocytosis. Overall, we show that Bfc serves as a Srp co-factor to upregulate the transcription of the crq encoded receptor, and consequently boosts macrophage efferocytosis in response to excessive apoptosis. Therefore, this study clarifies how phagocytes integrate apoptotic cell signals to mediate efferocytosis.

Non-immunological biomarkers for assessment of villous abnormalities in patients with celiac disease

BACKGROUND AND AIM

Demonstration of villous abnormalities is an essential component of diagnosis of celiac disease (CeD) that requires duodenal biopsies. There is a need for non-invasive biomarker(s) that can predict the presence of villous abnormalities.

METHODS

Levels of plasma citrulline, plasma intestinal fatty acid binding protein (I-FABP), and serum regenerating gene 1α (Reg1α) were estimated in treatment naïve patients with CeD and controls. The levels of these biomarkers and their cyclical pattern were validated in a predicted model of enteropathy. Optimum diagnostic cut-off values were derived, and the results were further validated in a prospective validation cohort.

RESULTS

While level of plasma citrulline was significantly lower, the levels of plasma I-FABP and serum Reg1α were significantly higher in patients with CeD (n = 131) in comparison with healthy (n = 216) and disease controls (n = 133), and their levels reversed after a gluten-free diet (GFD). In the model of predicted enteropathy (n = 70), a sequential decrease and then increase in the level of plasma citrulline was observed; such a sequential change was not observed with I-FABP and Reg1α. The diagnostic accuracy for prediction of presence of villous abnormality was 89% and 78% if citrulline level was  ≤ 30 μM/L and I-FABP levels were ≥ 1100 pg/mL, respectively. The results were validated in a prospective validation cohort (n = 104) with a sensitivity and specificity of 79.5% and 83.1%, respectively, for predicting villous abnormalities of modified Marsh grade > 2 at calculated cut-off values of citrulline and I-FABP.

CONCLUSIONS

Plasma citrulline  ≤ 30 μM/L is the most consistent, highly reproducible non-invasive biomarker that can predict the presence of villous abnormality and has the potential for avoiding duodenal biopsies in 78% patients suspected to have CeD.

Ultrasensitive detection of drug resistant cancer cells in biological matrixes using an amperometric nanobiosensor

Multidrug resistance (MDR) is a key issue in the failure of cancer chemotherapy and its detection will be helpful to develop suitable therapeutic strategies for cancer patients and overcome the death rates. In this direction, we designed a new amperometric sensor (a medical device prototype) to detect drug resistant cancer cells by sensing "Permeability glycoprotein (P-gp)". The sensor probe is fabricated by immobilizing monoclonal P-gp antibody on the gold nanoparticles (AuNPs) conducting polymer composite. The detection relies on a sandwich-type approach using a bioconjugate, where the aminophenyl boronic acid (APBA) served as a recognition molecule which binds with the cell surface glycans and hydrazine (Hyd) served as an electrocatalyst for the reduction of H2O2 which are attached on multi-wall carbon nanotube (MWCNT) (APBA-MWCNT-Hyd). A linear range for the cancer cell detection is obtained between 50 and 100,000 cells/mL with the detection limit of 23±2 cells/mL. The proposed immunosensor is successfully applied to detect MDR cancer cells (MDRCC) in serum and mixed cell samples. Interferences by drug sensitive (SKBr-3 and HeLa), noncancerous cells (HEK-293 and OSE), and other chemical molecules present in the real sample matrix are examined. The sensitivity of the proposed immunosensor is excellent compared with the conventional reporter antibody based assay.

Quantitative assessment of prion infectivity in tissues and body fluids by real-time quaking-induced conversion

Prions are amyloid-forming proteins that cause transmissible spongiform encephalopathies through a process involving the templated conversion of the normal cellular prion protein (PrP(C)) to a pathogenic misfolded conformation. Templated conversion has been modelled in several in vitro assays, including serial protein misfolding amplification, amyloid seeding and real-time quaking-induced conversion (RT-QuIC). As RT-QuIC measures formation of amyloid fibrils in real-time, it can be used to estimate the rate of seeded conversion. Here, we used samples from deer infected with chronic wasting disease (CWD) in RT-QuIC to show that serial dilution of prion seed was linearly related to the rate of amyloid formation over a range of 10(-3) to 10(-8) µg. We then used an amyloid formation rate standard curve derived from a bioassayed reference sample (CWD+ brain homogenate) to estimate the prion seed concentration and infectivity in tissues, body fluids and excreta. Using these methods, we estimated that urine and saliva from CWD-infected deer both contained 1-5 LD50 per 10 ml. Thus, over the 1-2 year course of an infection, a substantial environmental reservoir of CWD prion contamination accumulates.

Quantitation of human heme oxygenase (HO-1) copies by competitive RT-PCR

The authors have developed a system for quantifying human HO-1 mRNA in samples limited in cell number and/or mRNA copies. Total RNA from human liver was used to develop the system. The RNA is reverse transcribed and amplified by PCR in a tube also containing an internal standard obtained by deleting 50 base pairs from the original human gene. After amplification the two templates are resolved and quantified. When the internal standard is present in the reaction mixture, the ratio of amplified sample to internal standard is proportional to the amount of sample RNA making it possible to calculate the number of specific mRNA molecules.

Novel durum wheat genes up-regulated in response to a combination of heat and drought stress

We report the effect of heat, drought and combined stress on the expression of a group of genes that are up-regulated under these conditions in durum wheat (Triticum turgidum subsp. durum) plants. Modulation of gene expression was studied by cDNA-AFLP performed on RNAs extracted from flag leaves. By this approach, we identified several novel durum wheat genes whose expression is modulated under different stress conditions. We focused on a group of hitherto undescribed up-regulated genes in durum wheat, among these, 7 are up-regulated by heat, 8 by drought stress, 15 by combined heat and drought stress, 4 are up-regulated by both heat and combined stress, and 3 by both drought and combined stress. The functional characterization of these genes will provide new data that could help the developing of strategies aimed at improving durum wheat tolerance to field stress.

Identification of candidate genes associated with senescence in durum wheat (Triticum turgidum subsp. durum) using cDNA-AFLP

Senescence is an integrated response of plants to various internal (developmental) and external (environmental) signals. It is a highly regulated process leading eventually to the death of cells, single organs such as leaves, or even whole plants. In cereals, which are monocarpic plants, senescence represents the final stage of development. In order to study senescence in durum wheat (Triticum turgidum subsp. durum), a cDNA-AFLP analysis was performed. The transcription profiles of plants at different developmental stages (flowering and senescent) were compared. About 2000 cDNA fragments, ranging in size from 160 to 1900 bp, were reproducibly detected. This allowed the identification of 57 differentially expressed cDNAs corresponding to genes belonging to different functional categories related to cellular metabolism, transcription, maintenance of DNA structure, transport and signal transduction. This paper reports the identification of novel durum wheat candidate genes involved in the senescence process, and provides new information about the senescence programme of this important crop species.

Phosphorylation of phospholamban and troponin I through 5-HT4 receptors in the isolated human atrium

We studied the mRNA expression and function of 5-hydroxytryptamine (5-HT) receptors as well as their signal transduction in right atrial tissue from patients undergoing cardiac surgery and right ventricular tissue from human donor hearts. In isolated, electrically driven strips from human right atrium, 5-HT exerted concentration-dependent positive inotropic effects (EC(50) value = 0.10 +/- 0.01 microM) and hastened relaxation (positive lusitropic effect). The 5-HT(4) receptor antagonists SB203186 or GR125487 antagonised these effects. 5-HT (2 microM) increased the content of cyclic adenosine monophosphate (cAMP) from 6.86 +/- 1.36 to 19.1 +/- 2.45 pmol/mg protein (n = 6, p < 0.05) but did not alter the tissue content of inositol-1,4,5-trisphosphate (IP(3)). With reverse transcription polymerase chain reaction, mRNAs coding for the 5-HT(4) receptor splice variants 5-HT(4(a)), 5-HT(4(b)) and 5-HT(4(c)) were detected in human right atrium and right ventricle. 5-HT(2A) mRNA only was measurable in human atrium. Expression level of total 5-HT(4) receptor mRNA in the right ventricle amounted to 41% (n = 5-8) of that in the right atrium. 5-HT (2 microM) increased the atrial phosphorylation states of phospholamban to 168% at serine-16 and to 150% at threonine-17 (n = 4; p < 0.05) and of the inhibitory subunit of troponin to 150% (n = 6; p < 0.05). In conclusion, the positive inotropic and lusitropic effects of 5-HT in electrically driven human right atria are mediated via 5-HT(4) receptors. These effects are accompanied by and probably due to an increase in cAMP content and the subsequent elevation of the phosphorylation state of Ca(2+) regulatory proteins.

Intron splicing in 5' untranslated region of the rolA transcript in transgenic apple

The rolA gene encoded on the Ri plasmid of Agrobacterium rhizogenes causes developmental alterations, including dwarfing characteristics in the transgenic plants. In an attempt to introduce dwarfing characteristics into apple rootstocks for breeding purposes, the rolA gene was incorporated into the apple rootstock M26 and obtained four transgenic clones. All the clones exhibited reduced growth compared to untransformed control plants but different degree of dwarfing and wrinkled leaves. In the present study, expression of the rolA gene was further investigated by analysing the structure of the rolA transcript and the levels of the rolA mRNAs from these clones. The nucleotide (nt) sequence of the rolA transcript showed two forms of the transcript: one, the unspliced form, was co-linear with the rolA sequence in the genomic DNA; the other was spliced mRNA in which an 85-base pair (bp) intron sequence in the 5' untranslated region (5'UTR) was spliced out. The position of splicing is different from that in Arabidopsis thaliana but similar to the splicing site found in tobacco. The transcription start region of the rolA gene in apple was 206bp upstream of that in Arabidopsis and 277bp upstream to Nicotiana tabacum transcription start. A hairpin-like secondary structure and an upstream open reading frame (uORF) were revealed in the rolA 5'UTR. The levels of the rolA mRNA in the apple transgenic clones were analysed by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). The results showed slight variation in the shoot tissues of the transgenic clones.

Is human placenta proteoglycan remodeling involved in pre-eclampsia?

Impaired placento-fetal communication is a coherent symptom of exaggerated pre-eclampsia. The impact of the cellular expression of different glycosaminoglycans (GAGs) in this event on the placenta in pre-eclampsia is still obscure. This is the first study aimed at discovering the relationship between structural alterations of different sulfated GAGs at the molecular level and the development of pre-eclampsia in inflicted placenta. Sulfated GAGs were isolated and purified from control and pre-eclampsia placentas. The amount and the molecular weight of GAG in each tissue sample were measured. The polydispersity of the recovered GAG samples were determined by polyacrylamide gel electrophoresis. The disaccharide composition of chondroitin sulfate, dermatan sulfate and heparan sulfate were deduced by chondroitinase and heparinase depolymerization followed by liquid chromatography-mass spectrometry. The in vivo sulfo-modulation of GAGs in pre-eclampsia and control placenta were examined using RT-PCR to determine the transcription levels of different sulfotransferases involved in GAG biosynthesis. Marked differences in GAG sulfation patterns and mRNA level of encoding selected GAG O-sulfotransferases were observed in pre-eclampsia. These data suggest a linkage between pre-eclampsia and the observed alterations in placental GAGs and could provide new insights about the modulating role of GAGs in the development and the severity of placental pre-eclampsia.

Cytoskeleton and paclitaxel sensitivity in breast cancer: the role of beta-tubulins

The antineoplastic effect of paclitaxel is mainly related to its ability to bind the beta subunit of tubulin, thus preventing tubulin chain depolarization and inducing apoptosis. The relevance of the Class I beta-tubulin characteristics have also been confirmed in the clinical setting where mutations of paclitaxel-binding site of beta-tubulin Class I have been related to paclitaxel resistance in non small cell lung and ovarian cancers. In the present study, we verified the hypothesis of a relationship between molecular alterations of beta-tubulin Class I and paclitaxel sensitivity in a panel of breast cell lines with different drug IC(50). The Class I beta-tubulin gene cDNA has been sequenced detecting heterozygous missense mutations (exon 1 and 4) only in MCF-7 and SK-BR-3 lines. Furthermore, the expression (at both mRNA and protein level) of the different isotypes have been analyzed demonstrating an association between low cell sensitivity to paclitaxel and Class III beta-tubulin expression increasing. Antisense oligonucleotide (ODN) experiments confirmed that the inhibition of Class III beta-tubulin could at least partially increase paclitaxel-chemosensitivity. The hypothesis of a relationship between beta-tubulin tumor expression and paclitaxel clinical response has been finally verified in a series of 92 advanced breast cancer patients treated with a first line paclitaxel-based chemotherapy. Thirty-five percent (95% CI: 45-31) of patients with high Class III beta-tubulin expression showed a disease progression vs. only 7% of patients with low expression (35% vs. 7%, p < 0.002). Our study suggests that Class III beta-tubulin tumor expression could be considered a predictive biomarker of paclitaxel-clinical resistance for breast cancer patients.

Preclinical antitumor activity of the oral platinum analog satraplatin

PURPOSE

Satraplatin is an orally available platinum analog. The purpose of this study was to better characterize satraplatin's preclinical antitumor efficacy in a variety of sensitive and resistant human tumor cell lines and in a prostate cancer xenograft model and to evaluate the effect of satraplatin on PSA expression and/or secretion in a prostate cancer cell line.

METHODS

Satraplatin and its primary metabolite JM-118 were preclinically tested for their cytotoxic activity in a range of cancer cells including: human prostate, those forming the NCI drug screening panel, and those resistant to anti-cancer drugs. Also, the antiproliferative efficacy of satraplatin was tested in vivo in a human prostate cancer model. The effect of satraplatin and JM-118 on PSA transcription was measured by quantitative real time PCR.

RESULTS

Satraplatin and JM-118 inhibited in vitro and in vivo the growth of prostate cancer cells in a dose-dependent fashion. The IC50 cytotoxicity values for satraplatin ranged from 1 to 3 microM for androgen-insensitive cells and was 11 microM for the androgen-sensitive cell line. Interestingly, JM-118 was up to 16-fold more potent than satraplatin. Oral administration of satraplatin to nude mouse PC-3 xenograft models inhibited the growth of these human tumors. Satraplatin had no direct effect on PSA transcription and the observed decrease in secreted PSA correlated with a decrease in cell number. When evaluated in the NCI drug-screening panel, satraplatin was most active in leukemia and small cell lung cancer cell lines. Both satraplatin and JM-118 were tested on cells resistant to chemotherapeutic agents. Satraplatin and JM-118 were equally active in the cisplatin-resistant A129cp80 ovarian carcinoma cell line, with activity comparable to that observed in the parent line. Neither expression of MDR1, BCRP, MRP1, nor altered tubulin or topoisomerase I were found to mediate resistance to satraplatin or JM-118. Although these resistance mechanisms contribute to drug resistance for a number of chemotherapeutics, they do not appear to play a role in satraplatin resistance.

CONCLUSIONS

These results demonstrate that satraplatin and JM-118 have preclinical antitumor activity in human prostate cancer and other tumor types as well, including several cell lines displaying drug resistance to cisplatin, docetaxel and mitoxantrone. In addition, the results suggest that PSA should be further evaluated as a relevant marker of clinical response in patients with prostate cancer treated with satraplatin.

Effect of the anti-tumor necrosis factor-alpha antibody infliximab on the ex vivo mucosal matrix metalloproteinase-proteolytic phenotype in inflammatory bowel disease

BACKGROUND

Previous studies have shown an upregulation of matrix metalloproteinases (MMPs) in intestinal tissue of patients with inflammatory bowel disease (IBD) and significant clinical improvement after administration of the anti-TNF-a antibody infliximab. The aims of our study were to determine expression and secretion of MMP-1, -2, -3, -9, and their inhibitors TIMP-1, -2 by IBD versus control intestinal mucosa ex vivo and to assess the regulatory capacity by infliximab of the proteolytic phenotype.

METHODS

Intestinal mucosal explants from 20 IBD and 15 control patients were cultured with or without infliximab and/or the T-cell activator pokeweed mitogen (PWM). Explants and culture supernatants were analyzed for MMPs, TIMPs, and TNF-alpha protein, activity and/or mRNA levels. All patients were genotyped for functional TNF-alpha, MMP, and TIMP single nucleotide polymorphism (SNP) loci.

RESULTS

Expression of MMP and TIMP protein/activity in basal medium was higher in IBD versus control explants. Dependent on genotype at SNP loci, infliximab downregulated MMP-1, -3, and -9 relative to TIMP-1 and -2 and also decreased MMP-1 and -3 activities, while PWM enhanced these levels, partly counteracted again by infliximab. The expression of MMP-2 relative to TIMP did not change by treatment with infliximab and/or PWM.

CONCLUSIONS

The high expression of MMPs in patients with IBD suggests a role for these proteinases in the pathogenesis of this disease. Infliximab seems to induce a genotype-associated matrix protective phenotype, which may contribute to the observed therapeutic efficacy of this drug in IBD, particularly at the mucosal surface.

Dehydration increases L-type Ca(2+) current in rat supraoptic neurons

The magnocellular neurosecretory cells of the hypothalamus (MNCs) regulate water balance by releasing vasopressin (VP) and oxytocin (OT) as a function of plasma osmolality. Release is determined largely by the rate and pattern of MNC firing, but sustained increases in osmolality also produce structural adaptations, such as cellular hypertrophy, that may be necessary for maintaining high levels of neuropeptide release. Since increases in Ca(2+) current could enhance exocytotic secretion, influence MNC firing patterns, and activate gene transcription and translation, we tested whether Ca(2+) currents in MNCs acutely isolated from the supraoptic nucleus (SON) of the hypothalamus are altered by 16-24 h of water deprivation. A comparison of whole-cell patch-clamp recordings demonstrated that dehydration causes a significant increase in the amplitude of current sensitive to the L-type Ca(2+) channel blocker nifedipine (from -56 +/- 6 to -99 +/- 10 pA; P < 0.001) with no apparent change in other components of Ca(2+) current. Post-recording immunocytochemical identification showed that this increase in current occurred in both OT- and VP-releasing MNCs. Radioligand binding studies of tissue from the SON showed there is also an increase in the density of binding sites for an L-type Ca(2+) channel ligand (from 51.5 +/- 4.8 to 68.1 +/- 4.1 fmol (mg protein)(-1); P < 0.05), suggesting that there was an increase in the number of L-type channels on the plasma membrane of the MNCs or some other cell type in the SON. There were no changes in the measured number of binding sites for an N-type Ca(2+) channel ligand. Dehydration was not associated with changes in the levels of mRNA coding for Ca(2+) channel alpha(1) subunits. These data are consistent with the hypothesis that a selective increase of L-type Ca(2+) current may contribute to the adaptation that occurs in the MNCs during dehydration.

Resistance to glycopeptide antibiotics in the teicoplanin producer is mediated by van gene homologue expression directing the synthesis of a modified cell wall peptidoglycan

Glycopeptide resistance has been studied in detail in enterococci and staphylococci. In these microorganisms, high-level resistance is achieved by replacing the C-terminal D-alanyl-D-alanine of the nascent peptidoglycan with D-alanyl-D-lactate or D-alanyl-D-serine, thus reducing the affinities of glycopeptides for cell wall targets. Reorganization of the cell wall is directed by the expression of the van gene clusters. The identification of van gene homologs in the genomes of several glycopeptide-producing actinomycetes suggests the involvement of a similar self-resistance mechanism to avoid suicide. This report describes a comprehensive study of self-resistance in Actinoplanes teichomyceticus ATCC 31121, the producer of the clinically relevant glycopeptide teicoplanin. A. teichomyceticus ATCC 31121 showed a MIC of teicoplanin of 25 microg/ml and a MIC of vancomycin of 90 microg/ml during vegetative growth. The vanH, vanA, and vanX genes of A. teichomyceticus were found to be organized in an operon whose transcription was constitutive. Analysis of the UDP-linked peptidoglycan precursors revealed the presence of UDP-glycomuramyl pentadepsipeptide terminating in D-alanyl-D-lactate. No trace of precursors ending in d-alanyl-d-alanine was detected. Thus, the van gene complex was transcribed and expressed in the genetic background of A. teichomyceticus and conferred resistance to vancomycin and teicoplanin through the modification of cell wall biosynthesis. During teicoplanin production (maximum productivity, 70 to 80 microg/ml), the MIC of teicoplanin remained in the range of 25 to 35 microg/ml. Teicoplanin-producing cells were found to be tolerant to high concentrations of exogenously added glycopeptides, which were not bactericidal even at 5,000 microg/ml.

Drought stress response in wheat: physiological and molecular analysis of resistant and sensitive genotypes

Water deficit is a severe environmental stress and the major constraint on plant productivity with an evident effect on plant growth. The aim of this work was to study Triticum and Aegilops seedlings differing in their response to drought stress at the physiological and molecular levels. The identification of resistant and sensitive genotypes was firstly based on the relative water content (RWC) measurement. Further characterization of genotypes contrasting in their response to water stress was performed at the physiological level by determination of RWC, water loss rate (WLR) and free proline content after different hours of dehydration. Modification in the expression level of five dehydrin (DHN) genes was also analysed by reverse transcription-polymerase chain reaction (RT-PCR). Five cDNAs coding for different DHNs were identified and characterized. These genes are not expressed in the well-watered plants, but only in the stressed plants. Four of these cDNAs are related to novel DHN sequences. The results obtained clearly indicate a relation between the expression of these genes and tissue water content. In particular, in the resistant genotypes the expression of DHN genes is initiated even though tissue hydration levels are still high, indicating also in wheat the involvement of these proteins in water retention.

Inhibitory effect of curcumin onMDR1 gene expression in patient leukemic cells

When patients with cancers are treated with chemotherapeutic agents a long time, some of the cancer cells develop the multidrug resistance (MDR) phenotype. MDR cancer cells are characterized by the overexpression of multidrug resistance1(MDR1) gene which encodes P-glycoprotein (Pgp), a surface protein of tumor cells that functions to produce an excessive efflux and thereby an insufficient intracellular concentration of chemotherapeutic agents. A variety of studies have sought potent MDR modulators to decrease MDR1 gene expression in cancer cells. Our previous study has shown that curcumin exhibits characteristics of a MDR modulator in KB-V1 multidrug-resistant cells. The aim of this study was to further investigate the effect of curcumin on MDR1 gene expression in patient leukemic cells. The leukemic cells were collected from 78 childhood leukemia patients admitted at Maharaj Nakorn Chiang Mai Hospital, Chiang Mai, Thailand, in the period from July 2003 to February 2005. There were 61 cases of acute lymphoblastic leukemia (ALL), 14 cases of acute myeloblastic leukemia (AML), and 3 cases of chronic myelocytic leukemia (CML). There were 47 males and 31 females ranging from 1 to 15 years old. Bone marrows were collected. The leukemic cells were separated and cultured in the presence or absence of 10 microM curcumin for 48 hours. MDR1 mRNA levels were determined by RT-PCR. It was found that curcumin reduced MDR1 gene expression in the cells from 33 patients (42%). Curcumin affected the MDR1 gene expression in 5 of 11 relapsed cases (45%), 10 of 26 cases of drug maintenance (38%), 7 of 18 cases of completed treatment (39%), and 11 of 23 cases of new patients (48%). The expression levels of MDR1 gene in leukemic patient cells as compared to that of KB-V1 cells were classified as low level (1-20%) in 5 of 20 cases (25%), medium level (21-60%) in 14 of 32 cases (44%), and high level (61-100%) in 14 of 20 cases (70%). In summary, curcumin decreased MDR1 mRNA level in patient leukemic cells, especially in high level of MDR1 gene groups. Thus, curcumin treatment may provide a lead for clinical treatment of leukemia patients in the future.

Quantitative real-time RT-PCR data analysis: current concepts and the novel "gene expression's CT difference" formula

For quantification of gene-specific mRNA, quantitative real-time RT-PCR has become one of the most frequently used methods over the last few years. This article focuses on the issue of real-time PCR data analysis and its mathematical background, offering a general concept for efficient, fast and precise data analysis superior to the commonly used comparative CT (DeltaDeltaCT) and the standard curve method, as it considers individual amplification efficiencies for every PCR. This concept is based on a novel formula for the calculation of relative gene expression ratios, termed GED (Gene Expression's CT Difference) formula. Prerequisites for this formula, such as real-time PCR kinetics, the concept of PCR efficiency and its determination, are discussed. Additionally, this article offers some technical considerations and information on statistical analysis of real-time PCR data.

Hormonal activity of combinations of genistein, bisphenol A and 17β-estradiol in the female Wistar rat

Phytoestrogens have been described as weak estrogens, selective estrogen receptor mediators (SERMs) or to exhibit antiestrogenic properties. However, information about their activity in combination with xenoestrogens and 17beta-estradiol in vivo, is limited. Therefore, the combinatory activity of the phytoestrogen genistein (Gen), the industrial chemical bisphenol A (BPA), and ethinylestradiol (EE) in ovariectomized Wistar rats was analyzed in this study. All compounds were administered orally on three consecutive days (EE at 30 microg, Gen at 100 mg and BPA at 200 mg per kg body weight per day). The pure antiestrogen fulvestrant (3 mg/kg) served as estrogen receptor (ER) antagonist control. Effects on uterine wet weight, height of the uterine epithelium, uterine clusterin (Clu) and complement C3 expression, and the height of the vaginal epithelium were examined. Treatment with Gen alone resulted in a moderate stimulation of uterine weight; in the vagina the height of the epithelium was strongly stimulated. BPA did not stimulate any of the above-mentioned parameters significantly. In combination with EE, Gen acted on most of the analyzed parameters in an additive manner, whereas BPA significantly antagonized the effects of EE on the uterine epithelium and uterine Clu expression. Given in combination with Gen, BPA was also able to antagonize the stimulatory effect of Gen on the uterine epithelium. In summary, our results demonstrate that Gen, in contrast to BPA, does not exhibit any antiestrogenic properties, even if given at high concentrations. The results of this study characterize BPA as a functional antiestrogen, very likely the result of a lack of ability to activate ER-mediated transactivation after binding to the receptor. This is not the case for Gen. Our results point to the involvement of complex molecular mechanisms in the action of Gen. These mechanisms, especially the role of ERbeta have to be characterized in further investigations.

Reversal of P-glycoprotein-mediated multidrug resistance in cancer cells by the c-Jun NH2-terminal kinase

A significant impediment to the success of cancer chemotherapy is multidrug resistance (MDR). A typical form of MDR is attributable to the overexpression of membrane transport proteins, such as P-glycoprotein, resulting in an increased drug efflux. In this study, we show that adenovirus-mediated enhancement of the c-Jun NH2-terminal kinase (JNK) reduces the level of P-glycoprotein in a dose- and time-dependent manner. Protein turnover assay shows that the decrease of P-glycoprotein is independent of its protein stability. Instead, this occurs primarily at the mRNA level, as revealed by reverse transcription-PCR analysis. We find that P-glycoprotein down-regulation requires the catalytic activity of JNK and is mediated by the c-Jun transcription factor, as either pharmacologic inhibition of JNK activity or dominant-negative suppression of c-Jun remarkably abolishes the ability of JNK to down-regulate P-glycoprotein. In addition, electrophoretic mobility shift assay reveals that adenoviral JNK increases the activator protein binding activity of the mdr1 gene in the MDR cells. We further show that the decrease of P-glycoprotein level is associated with a significant increase in intracellular drug accumulation and dramatically enhances the sensitivity of MDR cancer cells to chemotherapeutic agents. Our study provides the first direct evidence that enhancement of the JNK pathway down-regulates P-glycoprotein and reverses P-glycoprotein-mediated MDR in cancer cells.

Aberrant transcription from an unrelated promoter can result in MDR-1 expression following drug selection in vitro and in relapsed lymphoma samples

The development of drug resistance in the treatment of cancer remains a major problem. The hallmark of multidrug resistance is cross-resistance to multiple structurally unrelated compounds. The MDR-1 gene encoding P-glycoprotein mediates one of the most extensively studied mechanisms of drug resistance. Previous studies led to the proposal that two promoters control expression of the MDR-1 gene, and these were designated the upstream and downstream promoters. In the present article, we provide evidence that transcripts originating from the putative upstream promoter of MDR-1 are in fact aberrant transcripts whose expression is regulated by nearby genomic sequences that include a human endogenous retroviral long terminal repeat (LTR). Expression of this LTR occurs in all cells. We show that following drug selection, especially in cases where gene amplification has occurred, MDR-1 transcripts can begin near this retroviral LTR with transcription proceeding in the direction opposite of the usual LTR transcription. Because expression of these aberrant MDR-1 transcripts (AMT) is found primarily in drug-resistant cell lines, we conclude that the development of drug resistance or the attendant drug exposure might have a role in the activation of this phenomenon or the selection of cells expressing AMTs. Demonstration of similar aberrant transcripts in tumor samples obtained from patients with relapsed lymphoma suggests that this phenomenon may also occur clinically.

High density lipoproteins downregulate basic fibroblast growth factor production and release in minimally oxidated-LDL treated smooth muscle cells

Increase in plasma low density lipoprotein (LDL) levels and/or decrease in high density lipoprotein (HDL) levels are major risk factors for the development of atherosclerosis. An oxidative modification of LDL represents a key process in atherogenesis. It is well known that the LDL/HDL ratio is more important than the individual LDL and HDL levels to predict atherosclerosis. The purpose of our study was to investigate the effects of mildly oxidized LDL (minimally modified LDL: MM-LDL) and HDL, administrated alone or in combination, on the production and release of basic fibroblast growth factor (bFGF) by bovine aortic smooth muscle cells (SMCs) in culture. MM-LDL and HDL have opposite effects on aortic SMCs: MM-LDL increases both bFGF production and release and SMC proliferation, while HDL decreases both bFGF production and release and SMC proliferation. The effects of either MM-LDL or HDL on SMCs are mediated through a Gi-protein-coupled receptor. The simultaneous treatment of SMCs with MM-LDL and HDL (MM-LDL/HDL ratio=4.0) produced the inhibition of MM-LDL effects. Our data suggest that the protective role of HDL could also be exerted through the inhibition of the pro-atherosclerotic effects of MM-LDL on SMCs.

Dynamic changes in cellular and microenvironmental composition can be controlled to elicit in vitro human hematopoietic stem cell expansion

OBJECTIVE

The absence of effective strategies for the ex vivo expansion of human hematopoietic stem cells (HSCs) limits the development of many cell-based therapies. Prior attempts to stimulate HSC expansion have focused on media supplementation using cytokines and growth factors. In these cultures, cellular and microenvironmental compositions change with time. In this study, the impact of controlling these dynamic changes on HSC output is determined.

MATERIALS AND METHODS

Cord blood-derived lin(-) cells were cultured for 8 days in serum-free medium supplemented with stem cell factor, Flt3 ligand, and thrombopoietin. Functional, phenotypic, and molecular (gene and protein) analyses were used to characterize dynamic changes in cellular and microenvironmental composition. The effects of these changes and the mechanism behind their effects on HSC expansion were assessed using a selection/media exchange-based global culture manipulation (GCM) technique.

RESULTS

We show that the direct secretion of negative regulators by culture-generated lin(+) cells, and the indirect stimulation of cells to secrete negative regulators by culture-conditioned media, limits in vitro HSC generation. The GCM strategy was able to abrogate these effects to produce elevated numbers of LTC-ICs (14.6-fold relative to input), migrating rapid NOD/SCID repopulating cells (12.1-fold), and long-term NOD/SCID repopulating cells (5.2-fold).

CONCLUSIONS

Cellular and microenvironmental changes that occur during all in vitro HSC cultures can significantly affect HSC output through the direct or indirect secretion of negative regulators. This study provides insight into the mechanisms regulating HSC fate in vitro and describes a novel methodology to regulate overall in vitro microenvironmental dynamics to enable the generation of clinically relevant numbers of HSCs.

Rose (Rosa rugosa)-flower extract increases the activities of antioxidant enzymes and their gene expression and reduces lipid peroxidation

The effects of rose-flower extract on antioxidant enzymes were studied. The activities of catalase (CAT) and glutathione peroxidase (GPx) in 9-month-old senescence-accelerated mice (SAM mice) were lower than those in 6-month-old SAM mice. Therefore, 9-month-old SAM mice were the most appropriate targets for treatment with the rose-flower extract. The activities of CAT and GPx in SAM mice treated with rose-flower extract showed a marked increase in whole blood and liver. At the same time, the gene-expression level of CAT and GPx was upregulated in the liver, while malondialdehyde content in liver and brain decreased. Male SAM mice were more sensitive than female SAM mice. The mean and the longest lifespan of SAM mice were longer after treatment with rose-flower extract.Key word: anti-aging, CAT, GPx, lipid peroxidation.

Effect of tumor necrosis factor-alpha and interferon-gamma on intestinal P-glycoprotein expression, activity, and localization in Caco-2 cells

The P-glycoprotein (Pgp), a drug efflux pump, is expressed in intestinal epithelial cells, where it constitutes a barrier against xenobiotics. In inflammatory bowel disease, a dysregulation in the production of tumor necrosis factor (TNF)alpha and interferon (IFN)gamma, and an alteration of Pgp expression and activity have been reported. The aim of this study was to investigate the effects of TNF alpha and IFN gamma on intestinal Pgp expression, activity, and localization in Caco-2 cells grown on filters. TNF alpha induced both a strong time-dependent diminution (-56%) of MDR1 mRNA (semiquantitative reverse transcription polymerase chain reaction) and a significant decrease of unidirectional transport of rhodamine 123 after 48 h of exposure at 10 ng/mL. By confocal laser scanning microscopy, the Pgp was mainly localized to the apical plasma membrane of both control and TNF alpha-treated cells. By contrast, IFN gamma induced up-regulation of both mRNA MDR1 and Pgp protein expression without incidence on Pgp activity. Interestingly, a colocalization of Pgp with lateral F-actin was observed. Associated with TNF alpha, IFN gamma produced neither an antagonist nor synergistic effect on Pgp activity. In conclusion, our results demonstrate an inhibitory effect of TNF alpha and no effect of IFN gamma on Pgp transport activity using rhodamine 123 as a substrate. Mechanisms of action of these cytokines remain to be studied.

Quantification of MDR-1 gene expression in canine tissues by real-time reverse transcription quantitative polymerase chain reaction

MDR-1 gene product mediated multidrug resistance is thought to play a major role in the outcome of chemotherapy in some canine tumors, especially malignant lymphoma. In the present study, MDR-1 RNA expression in normal lymph node and liver tissue as well as in tumor biopsies from 23 dogs with lymphomas and two dogs with liver tumors was measured by real-time RT-quantitative PCR. MDR-1 gene expression was detected in all samples analyzed. Comparably high MDR-1 RNA levels were measured in all normal liver tissues, one of the lymphomas and a cholangiocarcinoma. MDR-1 expression levels in canine lymphomas were found to vary over a wide range with most tumors expressing relative low levels. Interestingly, gastrointestinal lymphomas expressed higher MDR-1 RNA levels than multicentric lymphomas (p = 0.03). In conclusion, real-time RT-quantitative PCR appears to be a suitable method for sensitive and quantitative determination of MDR-1 gene expression in canine normal and neoplastic tissues.

Short on phosphate: plant surveillance and countermeasures

Metabolism depends on inorganic phosphate (P(i)) as reactant, allosteric effector and regulatory moiety in covalent protein modification. To cope with P(i) shortage (a common situation in many ecosystems), plants activate a set of adaptive responses to enhance P(i) recycling and acquisition by reprogramming metabolism and restructuring root system architecture. The physiology of P(i) starvation responses has become well understood, and so current research focuses on the initial molecular events that sense, transmit and integrate information about external and internal P(i) status. Recent studies have provided evidence for P(i) as a signaling molecule and initial insight into the coordination of P(i) deficiency responses at the cellular and molecular level.

T-cell lymphoma as a model for the use of histone deacetylase inhibitors in cancer therapy: impact of depsipeptide on molecular markers, therapeutic targets, and mechanisms of resistance

Depsipeptide (FK228) is a novel histone deacetylase inhibitor currently in clinical trials and the first to demonstrate clinical activity in patients. Responses have been observed in patients with T-cell lymphomas, despite prior treatment with multiple chemotherapeutic agents. To better understand the effects of histone deacetylase inhibitors on T-cell lymphoma, the human T-cell lymphoma cell line HUT78 was tested for sensitivity and molecular response to depsipeptide. Treatment with depsipeptide, as well as other histone deacetylase inhibitors, caused induction of histone acetylation, induction of p21 expression, and substantial apoptosis without significant cell cycle arrest. Treatment with the caspase inhibitor z-VAD-fmk significantly inhibited depsipeptide-induced apoptosis, enabling detection of cell cycle arrest. Treatment with depsipeptide increased expression of the interleukin-2 (IL-2) receptor, and combination with the IL-2 toxin conjugate denileukin diftitox resulted in more than additive toxicity. Cells selected for resistance to depsipeptide overexpressed the multidrug resistance pump, P-glycoprotein (Pgp). However, cells selected for resistance to depsipeptide in the presence of a Pgp inhibitor had a Pgp-independent mechanism of resistance. These studies confirm the activity of depsipeptide in a T-cell lymphoma model and suggest a general sensitivity of T-cell lymphoma to histone deacetylase inhibitors, an emerging new class of anticancer agents. (Blood. 2004;103:4636-4643)

Modulation of human multidrug-resistance MDR-1 gene by natural curcuminoids

BACKGROUND

Multidrug resistance (MDR) is a phenomenon that is often associated with decreased intracellular drug accumulation in patient's tumor cells resulting from enhanced drug efflux. It is related to the overexpression of a membrane protein, P-glycoprotein (Pgp-170), thereby reducing drug cytotoxicity. A variety of studies have tried to find MDR modulators which increase drug accumulation in cancer cells.

METHODS

In this study, natural curcuminoids, pure curcumin, demethoxycurcumin and bisdemethoxycurcumin, isolated from turmeric (Curcuma longa Linn), were compared for their potential ability to modulate the human MDR-1 gene expression in multidrug resistant human cervical carcinoma cell line, KB-V1 by Western blot analysis and RT-PCR.

RESULTS

Western blot analysis and RT-PCR showed that all the three curcuminoids inhibited MDR-1 gene expression, and bisdemethoxycurcumin produced maximum effect. In additional studies we found that commercial grade curcuminoid (approximately 77% curcumin, 17% demethoxycurcumin and 3% bisdemthoxycurcumin) decreased MDR-1 gene expression in a dose dependent manner and had about the same potent inhibitory effect on MDR-1 gene expression as our natural curcuminoid mixtures.

CONCLUSION

These results indicate that bisdemethoxycurcumin is the most active of the curcuminoids present in turmeric for modulation of MDR-1 gene. Treatment of drug resistant KB-V1 cells with curcumin increased their sensitivity to vinblastine, which was consistent with a decreased MDR-1 gene product, a P-glycoprotein, on the cell plasma membrane. Although many drugs that prevent the P-glycoprotein function have been reported, this report describes the inhibition of MDR-1 expression by a phytochemical. The modulation of MDR-1 expression may be an attractive target for new chemosensitizing agents.

Reverse transcription-polymerase chain reaction: an overview of the technique and its applications

The polymerase chain reaction (PCR) has galvanized molecular biologists by virtue of its ability to provide them with large quantities of any desired fragment (up to 11kb) of DNA. This power combined with its flexibility has also inspired many useful applications, including new methods of DNA sequencing, cloning and mutagenesis. One logical variation of PCR has been its application to the detection and analysis of messenger RNA by the addition of a reverse transcription step prior to performing PCR. Due to the exquisite sensitivity of PCR, reverse transcription-PCR (RT-PCR) has been used to characterize mRNAs previously undetectable by established methods of RNA analysis such as Northern hybridization and RNase protection assays. Furthermore, its capacity as a method of quantitative analysis is currently being developed. RT-PCR has also been used to diagnose the presence of certain diseases. Recently, RT-PCR has been employed to identify and isolate genes that are differentially expressed in different cells or environmental conditions.

Standard-curve competitive RT-PCR quantification of myogenic regulatory factors in chicken embryos

The reverse transcription-polymerase chain reaction (RT-PCR) is the most sensitive method used to evaluate gene expression. Although many advances have been made since quantitative RT-PCR was first described, few reports deal with the mathematical bases of this technique. The aim of the present study was to develop and standardize a competitive PCR method using standard-curves to quantify transcripts of the myogenic regulatory factors MyoD, Myf-5, Myogenin and MRF4 in chicken embryos. Competitor cDNA molecules were constructed for each gene under study using deletion primers, which were designed to maintain the anchorage sites for the primers used to amplify target cDNAs. Standard-curves were prepared by co-amplification of different amounts of target cDNA with a constant amount of competitor. The content of specific mRNAs in embryo cDNAs was determined after PCR with a known amount of competitor and comparison to standard-curves. Transcripts of the housekeeping -actin gene were measured to normalize the results. As predicted by the model, most of the standard-curves showed a slope close to 1, while intercepts varied depending on the relative efficiency of competitor amplification. The sensitivity of the RT-PCR method permitted the detection of as few as 60 MyoD/Myf-5 molecules per reaction but approximately 600 molecules of MRF4/Myogenin mRNAS were necessary to produce a measurable signal. A coefficient of variation of 6 to 19% was estimated for the different genes analyzed (6 to 9 repetitions). The competitive RT-PCR assay described here is sensitive, precise and allows quantification of up to 9 transcripts from a single cDNA sample.

Extensive normal copy number variation of a beta-defensin antimicrobial-gene cluster

Using a combination of multiplex amplifiable probe hybridization and semiquantitative fluorescence in situ hybridization (SQ-FISH), we analyzed DNA copy number variation across chromosome band 8p23.1, a region that is frequently involved in chromosomal rearrangements. We show that a cluster of at least three antimicrobial beta-defensin genes (DEFB4, DEFB103, and DEFB104) at 8p23.1 are polymorphic in copy number, with a repeat unit >/=240 kb long. Individuals have 2-12 copies of this repeat per diploid genome. By segregation, microsatellite dosage, and SQ-FISH chromosomal signal intensity ratio analyses, we deduce that individual chromosomes can have one to eight copies of this repeat unit. Chromosomes with seven or eight copies of this repeat unit are identifiable by cytogenetic analysis as a previously described 8p23.1 euchromatic variant. Analysis of RNA from different individuals by semiquantitative reverse-transcriptase polymerase chain reaction shows a significant correlation between genomic copy number of DEFB4 and levels of its messenger RNA (mRNA) transcript. The peptides encoded by these genes are potent antimicrobial agents, especially effective against clinically important pathogens, such as Pseudomonas aeruginosa and Staphylococcus aureus, and DEFB4 has been shown to act as a cytokine linking the innate and adaptive immune responses. Therefore, a copy number polymorphism involving these genes, which is reflected in mRNA expression levels, is likely to have important consequences for immune system function.

Expression of androgen receptor coactivators in normal and cancer prostate tissues and cultured cell lines

BACKGROUND

In prostate cancer cell lines, androgen receptor (AR) coactivators modulate the transcriptional activity of AR. However, very little is known about their expression in normal prostate tissue and during progression to cancer.

METHODS

AR and coactivators ARA54, ARA55, ARA70, and SRC1 RNA were analyzed by RT-PCR in normal and tumoral tissues of the same prostate, in prostate cell lines, and after hormonal treatments of prostate epithelial cells.

RESULTS

AR-coactivators were expressed in normal and tumoral tissues and in cultured prostate cells; only ARA55 expression was decreased in tumoral relative to normal tissue of all seven prostates analyzed. It was not expressed in LNCaP and DU145 cancer cells and low in PNT2 immortalized cells in which all coactivator's expression were down regulated by DHT and up regulated by E2. In addition, coactivator's expression was increased in hyperplastic relative to normal prostate fibroblasts.

CONCLUSIONS

ARA55 is both an AR coactivator and a focal adhesion protein (Hic-5). Its role in the progression of prostate carcinoma may therefore involve these two different functions. Its decrease in cancer tissue suggests that it plays a different role than that expected, namely, facilitate cell proliferation and therefore mobility and metastasis.

Estrogenic and antiestrogenic regulation of MMP-2 and MMP-13 mRNA in RUCA-I endometrial tumor cells in vitro and in vivo

We investigated the influence of estrogenic and antiestrogenic treatment on proteolytic activity--especially on MMP-2 and MMP-13--in the RUCA-I transplantable endometrial tumor model. Morphological studies demonstrate that RUCA-I cells are forming highly differentiated gland-like structures by remodelling and invading the underlying ECM. Estrogens upregulate the mRNA levels of MMP-2 and MMP-13 in the rat uterus. Treatment with the pure antiestrogen ICI 182,780 results in the downregulation of MMP-2 and MMP-13 mRNA. The same regulation for MMP-13 mRNA is found in vitro in RUCA-I cells. In contrast, in the transplantation tumor, the mRNA level of MMP-13 is repressed by estrogens and induced by ICI 182,780. MMP-2 mRNA is not regulated by hormones in the transplantation tumor and in RUCA-I cells. The divergent regulation suggests a varying influence of cell-cell-, cell-extracellular matrix interactions and soluble factors.

Validation and clinical implication of a quantitative real-time PCR determination of MDR1 gene expression: comparison with semi-quantitative PCR in 101 patients with acute myeloid leukemia

INTRODUCTION

The multidrug resistance protein 1 (MDR1) has the capacity to extrude chemotherapeutics and has been implicated in treatment failure in acute myeloid leukemia (AML). Previous methods for determination of MDR1 expression have included dye exclusion, demonstration of P-glycoprotein by flow cytometry and/or immunohistochemistry, and molecular polymerase chain reaction (PCR)-based assays for RNA expression. However, these assays have either proven difficult to standardize or tedious to perform. We have therefore designed a real-time quantitative (RQ)-PCR based assay measuring MDR1 gene expression and validated it in AML patients by direct comparison with a competitive reverse transcriptase polymerase chain reaction (RT-PCR) assay.

PATIENTS AND METHODS

Bone marrow or peripheral blood from 101 AML patients diagnosed (1987-96) at our department were assessed for quantitative expression of MDR1 employing TaqMan RQ-PCR. These data were compared with results obtained by a semi-quantitative competitive PCR assay employing an artificial internal RNA construct.

RESULTS

While the RQ-PCR method was able to determine MDR1 gene expression in a continuous fashion over five logs, the semi-quantitative PCR only yielded data in a discontinuous fashion and over four logs at best. Compared with the MDR1 positive and negative cell lines 8226 DOX40 and REH AML cells exhibited variation of 10 PCR cycles, equivalent to a 1000-fold difference. A significant correlation was observed between the two methods, Spearman's correlation coefficient = -0.502, P-value = 10-5.

CONCLUSION

We conclude that, RQ-PCR is a novel methodology, which enables sensitive and quantitative measurement of MDR1 gene expression. This assay is moreover suitable because of its high throughput for longitudinal follow-up and large number of patients.

Multidrug resistance modulators PSC 833 and CsA show differential capacity to induce apoptosis in lymphoid leukemia cell lines independently of their MDR phenotype

Among the mechanisms that induce multidrug resistance (MDR), one of those most frequent is over-expression of a phosphoglycoprotein (Pgp) encoded in the mouse by the mdr-1 and mdr-3 genes. We have demonstrated that cyclosporin-A (CsA) as well as its analogue PSC 833 were able to revert the MDR phenotype in murine cell lines resistant to vincristine (LBR-V160) or doxorubicin (LBR-D160). The aim of this work was to evaluate the ability of PSC 833 and CsA to modulate mdr-1, mdr-3 and mrp-1 genes as well as to induce apoptosis analyzing the mechanism involved in the above tumor cell lines. By semi-quantitative RT-PCR, we demonstrated that mdr-3 was over-expressed in both resistant lines while mdr-1 was over-expressed only in LBR-V160; in contrast, mrp-1 expression was not evidenced in any of the cell lines. After treatment with 0.1 microg ml(-1) of either PSC 833 or CsA, LBR-V160 showed no changes in mdr-1 but decreased mdr-3 expression, while LBR-D160 failed to display any modification in the expression of these genes. Apoptosis was evidenced by fluorescence microscopy, S minuscule accumulation and agarose gel electrophoresis. Our results demonstrated that CsA (1 microg ml(-1)) was able to induce apoptosis in all cell lines: 18.31% (+/-4.46) for LBR-, 25.96% (+/-5.24) for LBR-V160 and 27.36% (+/-4.12) for LBR-D160, while PSC 833 (1 microg ml(-1)) only induced apoptosis 21.51% (+/-5.73) in LBR-V160 cell line. The expression of Bcl-2 family proteins (Bcl-2, Bax and Bcl-x(L)) was analyzed by flow cytometry showing high expression of the three proteins which was not significantly modified after treatment with either PSC 833 or CsA on the sensitive as well as on the resistant cell lines. Single stranded conformation polymorphisms analysis of p53 (Trp53) gene in the cell lines showed no mutation in exons 5-8 of the tumor suppressor gene. We conclude that depending on the concentration used, PSC 833 and CsA may act either by modulating the mdr-3 gene (0.1 microg ml(-1)) or by direct impact on the cells through induction of apoptosis (1 microg ml(-1)), in the latter case through a mechanism that might act independent of the Bcl-2 family proteins.

Vascular endothelial growth factor increases the migration and proliferation of smooth muscle cells through the mediation of growth factors released by endothelial cells

BACKGROUND

Vascular endothelial growth factor (VEGF), a highly specific chemotactic and mitogenic factor for vascular endothelial cells (EC), appears to be involved in the development of atherosclerosis. The purpose of our study was to assess if VEGF might indirectly stimulate SMC migration and proliferation in a EC-SMC coculture system, through the mediation of growth factors released by EC.

METHODS

Bovine aortic SMC were cocultured with bovine aortic EC treated with hrVEGF, to assess SMC proliferation and migration. The release and mRNA expression of basic fibroblast growth factor (bFGF) and transforming growth factor beta(1) (TGFbeta(1)) were assessed by ELISA and PCR analysis.

RESULTS

hrVEGF (10 ng/ml), added to EC cocultured with SMC, induced a significant increase in tritiated thymidine uptake by SMC as compared to controls (P < 0.01) and a significant increase in SMC migration in respect to control (27%; P < 0.01). EC stimulated with hrVEGF increased the release and the expression of bFGF and decreased the release and the expression of TGFbeta(1) with a statistically significant difference in respect to controls (P < 0.001).

CONCLUSIONS

VEGF indirectly stimulates SMC proliferation and migration through the modulation of bFGF and TGFbeta(1) released by EC.

Androgen modulation of adhesion and antiadhesion molecules in PC-3 prostate cancer cells expressing androgen receptor

The metastatic spread of cancer cells involves a complex process of detachment via antiadhesion molecules and attachment and migration through adhesion. In the prostate, androgens are generally thought to contribute to the development and progression of prostate cancer by promoting cell proliferation and survival through poorly defined mechanisms. We have reported previously that PC-3 prostate cancer cells, which are unresponsive to androgens, show androgen-dependent detachment and ultimately apoptosis when stably transfected with a full-length human androgen receptor (AR) cDNA. We now demonstrate that treatment of these cells with 5alpha-dihydrotestosterone (DHT) for 24 or 48 h increased the expression of antiadhesion mucin MUC-1 at the cell surface as detected by flow cytometry with two independent antibodies. This increase in protein was concordant with up-regulation of MUC-1 mRNA in the AR-transfected PC-3 sublines, as determined by quantitative RT-PCR. Treatment with DHT for 48 h also down-regulated the cell surface expression of alpha2beta1-integrin but having little effect on the levels of alpha3beta1- and alpha5beta1-integrins. Androgen also decreased, in a dose-dependent manner, the adhesion of AR-transfected PC-3 cells to collagen type I, which was shown to be specifically inhibited by blocking antibody to alpha2beta1-integrin. The present data demonstrate that DHT can modulate expression of adhesion and antiadhesion molecules and suggest that this effect of androgen might contribute to prostate cancer progression.

A diagnostic tool for monitoring multidrug resistance expression in human tumor tissues

Studies on multidrug resistance (MDR) require a sensitive and quantitative assay of mRNA expression in clinical tumor samples. Based on the small size, heterogenity, and the possibility of partial degradation of clinical specimens, unambiguous data are often difficult to obtain. The aim of the present study was to develop a multiplex polymerase chain reaction (PCR) in combination with nested PCR for quantitative analyses of mRNA expression of MDR1, MRP (multidrug resistance protein), and DNA topoisomerase IIalpha in small amounts of tumor tissue. RNA samples extracted from the human cell line RPMI 8226 and its MDR sublines 8226/Dox6 and DOXint40c, that overexpress MDR1 and MRP, respectively, were used as model substrates. In the first step, cDNAs of the three genes as well as of the housekeeping gene beta-actin were simultaneously amplified in single tubes using 20 cycles of PCR after random-primed reverse transcription. When necessary, a second amplification step of the preamplified PCR products was employed using nested primer pairs. Primer competition was evaluated by analyses of serially diluted amounts of cDNA and at different numbers of PCR cycles. Based on the results obtained, this multiplex/nested PCR approach may provide a base for quantitative analyses of MDR1, MRP, and topoisomerase IIalpha mRNA expression in clinical tumor biopsies.

Up-regulation of polymeric immunoglobulin receptor mRNA in mammary epithelial cells by IFN-gamma

As shown in previous in vivo experiment, the amount of polymeric immunoglobulin receptor (pIgR), which mediates the transcytosis of pIgA across epithelial cells, is regulated by lactogenic hormones (PRL and cortisol) during the development of the mammary gland. In the present in vitro study, it appeared that these hormones were insufficient to induce the strong expression of the gene that we observed in vivo. Several papers have shown that IFN-gamma is a strong stimulator of pIgR gene expression in different models. In contrast, nothing is known of the effects of IFN-gamma on pIgR gene expression in the mammary gland. We report here that IFN-gamma strongly increased pIgR mRNA levels through a direct effect on mammary epithelial cells. We show that IFN-gamma activated not only Stat1 but also Stat5 and that expression of the pIgR and IRF-1 genes was strongly correlated following IFN-gamma stimulation in mammary epithelial cells. In conclusion, these experiments enabled the analysis of different types of regulation of pIgR gene expression in the mammary gland and suggest possible co-operation between circulating hormones and locally produced cytokines, leading to pIgR gene expression in the mammary gland.

Modulation of P-glycoprotein expression and function by curcumin in multidrug-resistant human KB cells

Multidrug resistance (MDR) is a phenomenon that is often associated with decreased intracellular drug accumulation in the tumor cells of a patient, resulting from enhanced drug efflux. It is often related to the overexpression of P-glycoprotein (Pgp) on the surface of tumor cells, thereby reducing drug cytotoxicity. In this study, curcumin was tested for its potential ability to modulate the expression and function of Pgp in the multidrug-resistant human cervical carcinoma cell line KB-V1. Western blot analysis and reverse transcription-polymerase chain reaction (RT-PCR) showed that treatment with 1, 5, and 10 microM curcumin for up to 72hr was able to significantly lower Pgp expression in KB-V1 cells. Curcumin (1-10 microM) decreased Pgp expression in a concentration-dependent manner and was also found to have the same effect on MDR1 mRNA levels. The effect of curcumin on Pgp function was demonstrated by rhodamine 123 (Rh123) accumulation and efflux in Pgp-expressing KB-V1 cells. Curcumin increased Rh123 accumulation in a concentration-dependent manner (1-55 microM) and inhibited the efflux of Rh123 from these cells, but did not affect the efflux of Rh123 from the wild-type drug-sensitive KB-3-1 cells. Treatment of drug-resistant KB-V1 cells with curcumin increased their sensitivity to vinblastine, which was consistent with an increased intracellular accumulation of Rh123. In addition, curcumin inhibited verapamil-stimulated ATPase activity and the photoaffinity labeling of Pgp with the prazosin analog [125I]iodoarylazidoprazosin in a concentration-dependent manner, demonstrating that curcumin interacts directly with the transporter. Thus, curcumin seems to be able to modulate the in vitro expression and function of Pgp in multidrug-resistant human KB-V1 cells. In summary, this study describes the duel modulation of MDR1 expression and Pgp function by the phytochemical curcumin, which may be an attractive new agent for the chemosensitization of cancer cells.

Characterization of androgen receptor and nuclear receptor co-regulator expression in human breast cancer cell lines exhibiting differential regulation of kallikreins 2 and 3

Accumulating evidence indicates that androgens and the androgen receptor modulate the development and progression of breast adenocarcinoma; however, the precise role and actions remain poorly defined. We examined previously the steroid hormone regulation of 2 known androgen-regulated kallikreins, KLK3 (encoding PSA) and KLK2 (encoding human kallikrein 2 or hK2) in BT-474, T-47D, ZR75-1, MCF-7, MFM-223 and BT-20 human breast cancer cells and found that they were differentially regulated, with the cells showing variable responses to androgen. To determine if this variable response was reflected by differences in androgen receptor, we characterized the expression of androgen receptor in these cells by Western blot analysis and saturation binding analysis. In addition, we sequenced androgen receptor cDNA from each of these cell lines to check whether any androgen receptor mutations were present. The expression of 11 nuclear receptor co-regulatory factors (SRC-1, AIB1, ARA24, ARA54, ARA55, ARA70, ARA160, FHL2, PDEF, NCoR1, SMRT) was compared in these cell lines by semi-quantitative RT-PCR to determine if the pattern of receptor co-activators or -repressors expressed in these cells might explain the differential regulation of KLK2 and KLK3. The levels of androgen receptor varied among the cell lines, but did not correlate with hK2 and PSA secretion determined previously. No mutations within the coding regions of the receptor were detected. With the exception of receptor expressed by MCF-7 cells, the polymorphic CAG repeat length was in the normal range. Every breast cancer cell line exhibited a distinct expression pattern of the nuclear receptor co-regulators examined raising the possibility that the relative levels of these co-activators/-repressors might differentially modulate androgen receptor transcriptional activity within the promoter/enhancer region of KLK2 and KLK3 of these cells.

Effect of hr-IL2 treatment on intestinal P-glycoprotein expression and activity in Caco-2 cells

Caco-2 cells were used to investigate the effect of human recombinant interleukin-2 (IL2) on intestinal P-glycoprotein (P-gp) transporter activity in-vitro. More specifically the efflux function of P-gp was studied by measuring the transepithelial transport of rhodamine-123, a fluorescent substrate of P-gp. Its transport was completely inhibited by two specific P-gp inhibitors, ciclosporin A and GG918, in our experiments. Conversely, these two specific P-gp inhibitors inhibited only 50% of transepithelial transport when [3H]vincristine was used as substrate. After Caco-2 cells were treated with 100 IU mL-1 (6.1 ng mL-1) IL2 for 24 h, a significant diminution (21%) of P-gp transporter function was observed with rhodamine-123 substrate. This effect was also confirmed after 48 and 72 h of exposure to IL2. However, for higher concentrations of IL2 (1000 and 5000 IU mL-1), diminution of P-gp function only occurred after a longer treatment period (48 h and more). The inhibitory effect of IL2 on P-gp activity was found to be independent of tight junction function as demonstrated by constant transepithelial electrical resistance (TEER) measurements for all experimental conditions encountered in this study (time and concentration of IL2 exposure). Furthermore, the MDR1 mRNA level was found to be strongly repressed in Caco-2 cells exposed with 1000 IU mL-1 IL2 for 72 h while the amount of MRP1 mRNA remained unchanged. In conclusion, acute incubation of Caco-2 cells with IL2 induced a decrease of P-gp transporter expression and activity.

Effect of interleukin-2 on intestinal P-glycoprotein expression and functionality in mice

P-glycoprotein (Pgp), an active drug transporter expressed in enterocytes, can reduce intestinal absorption of drugs. Until now, interleukin-2 (IL2) has been reported as a Pgp modulator only in vitro. The present study examines the effects in vivo of IL2 after chronic treatment on intestinal Pgp protein expression and activity. This work also describes the effects of IL2 on the oral bioavailability of a Pgp substrate (digoxin) and of a Pgp/CYP3A cosubstrate (saquinavir). Human recombinant interleukin-2 (rIL2), administered to mice at 9 million international units/kg by intraperitoneal route twice daily for 4 days, led to a decrease in intestinal Pgp protein expression evaluated by Western blot with C219 antibody. In an in vitro everted gut sac model, rIL2 pretreatment decreased the Pgp-mediated transport of rhodamine 123 across mouse intestine by 37%. Moreover, rIL2 pretreatment markedly raised the area under the curve of orally administered digoxin from 3.5 +/- 0.5 to 9.7 +/- 1.5 mg min l(-1) as a consequence of the reduction in intestinal Pgp activity. rIL2 treatment increased saquinavir bioavailability from 2.5 to 4.5%, showing that first-pass metabolism is not affected and that Pgp by itself has only a moderate effect on saquinavir oral bioavailability. In conclusion, rIL2 pretreatment reduces intestinal Pgp protein expression and activity in mice. However, the effect of such a treatment on drug bioavailability depends on the extent of their metabolism by CYP3A.